1. Field of the Invention
The present invention is generally directed to systems maximizing the utilization of materials having irregular and unpredictable flaws and other defects such as found in forest products, plate glass, sheet metal and the like. The invention is particularly directed to a lumber inspection and optimization system embodying an electro-optical scanner generating data indicative of the location and size of flaws, a man-operated flaw classification device generating data indicative of the flaw class, an order entry device receiving data indicative of the size and quality of the desired product, and an electronic processor generating data indicative of the locations where the inspected piece of lumber is to be cut for optimum product yield.
2. Prior art
The woodworking industries, such as the furniture, millwork and molding plants, are faced with maximizing the utilization of the available lumber. The requirements of the various woodworking industries vary over a considerable range dependent primarily upon their principle output or product. The requirements can range from clear, flaw-free board pieces to pieces which may contain certain classes of imperfections of given sizes. Further, each woodworking plant has requirements for a variety of sizes of board pieces to meet production requirements. The various board pieces are cut from larger boards which come to the plant or factory as unfinished boards. The unfinished boards inherently possess various classes of defects and imperfections, such as tight and loose knots, cracks, checks, splits, bark, stain, pitch pockets and the like. The problem facing each woodworking facility is the analysis of each incoming board to determine how it may be cut to most efficiently meet the production requirements of the particular plant or facility. Typically, this is done by an experienced human inspector who, having knowledge of the size and quality of board pieces required to meet the facility's production need, evaluates each board and makes an on-the-spot determination as to the most efficient way to cut the particular board. This method has limitations particularly when the board is relatively large and the production need complicated and diverse. Under these conditions, the inspector does not get a good overall perspective of the whole board and his evaluation takes place section by section. Production requirements further limit the time the human inspector has to inspect each board. Therefore, his optimization of any given board may be less than desired. Because of these factors, optimization by a human inspector is generally considered to be inefficient and not cost effective.
To overcome this deficiency, the prior art has disclosed a variety of systems to aid or replace the human inspector in identifying and evaluating flaws in forest products. Finlay et al in U.S. Pat. No. 3,120,861 "Method and Apparatus for Identifying and Evaluating Surface Characteristics of Forest Products" (Feb. 11, 1964) discloses a rudimentary system for identifying and evaluating surface characteristics of forest products and is expressly incorporated by reference. The Finlay et al system electro-optically scans the surface of the board to detect the flaws and then either marks the board where it is to be cut or actuates a saw to remove these flaws. This system only locates the flaws along the length axis of the board. Detection of objectionable flaws in the Finlay et al system is determined by the pulse amplitude of the detected flaw and a recurrence on at least three successive scans. A deficiency of this system is that some flaws are difficult to detect by scanning the surface and may go undetected while surface dirt or other surface characteristics, such as an unusually dark grain, may be detected as a flaw resulting in a waste of material.
The concept of utilizing a computer for optimizing the cutting of lumber is introduced by Buss et al in U.S. Pat. No. 3,329,181 "Apparatus and Method for Cutting Assorted Length from Material Having Irregular and Random Defects" (July 4, 1967), the disclosure of which is expressly incorporated by reference. In the Buss et al system, the flaws are manually located by an inspector using an electro-mechanical scanner which generates electrical signals compatible with a computer indicative of the flaw's location. The inspector locates the flaw and marks the coordinates of the upper right-hand corner and lower left-hand corner of an imaginary rectangle encompassing the flaw. The inspector's control also contains a button whereby he may indicate that the indicated flaw is useable incertain inferior grades of stock needed by the plant or facility. The computer stores the size, location and class of defect selected by the inspector and then, in accordance with a predetermined program, determines how the board should be cut for optimum utilization. The computer program contains the size and grade of the board pieces required, as well as the number of each kind of piece necessary to meet its production requirements. Each board piece is weighted in the computation processes according to any of several parameters, such as the monetary value of the particular size and grade, a priority based on the difficulty of obtaining the specific size and grade, as well as the number of pieces required. In addition to determining how the board should be cut, the computer remembers the number of pieces of each kind yielded by that particular board. This information provides an inventory check and also can be input back into the computer program to readjust the arbitrary priority of each type of board to keep the output relatively balanced. Computer programs to perform this type of function are known in the art. Brichard et al in U.S. Pat. No. 3,490,147 "Method for Optimally Cutting Successive Panels in Pieces from a Sheet or Strip" Jan. 20, 1970), the disclosure of which is expressly incorporated by reference, as well as Buss, teach using computers for optimizing the cutting of sheets or strips in accordance with predetermined programs wherein the various sizes and grades have weighted values. The concept for using a computer for optimizing the cutting of lumber for maximum yield is also found in published literature. Typical examples are Englerth and Dummire "Programming for Lumber Yield", Forest Products Journal, Vol. 16, No. 9, Sept. 1966--Hallock and Bulgrin, "Tomorrow: Computer Made Sawing Decisions?", Forest Products Journal, Vol. 20, No. 9, Sept. 1970--Hafley and Hanson, "Optimum Sequence of Cutting Bills", Forest Products Journal, Vol. 23, No. 8, August 1973, each of which are expressly incorporated by reference. These computer programs can be adjusted for maximum monetary yield, maximum useable lumber or maximum yield for specific sizes in predetermined proportions.
The problems of the prior art systems include flaw detection and classification, as well as imparting the required information to the computer in a fast and efficient manner. The disclosed system combines the judgment capabilities of a human inspector with the speed of an electro-optical scanner in a manner to provide the proper information to the computer in a usable form in the most efficient manner.